Improvement in processes for canning food



UNITED STATES PATENT QFFICE.

HENRY WARDEN, or HAnNIBAL, MISSOURI.

IMPROVEMENT IN PROCESSES FOR CANNING FOOD.

Specification forming part of Letters Patent No. 223,083,1l atedDecember 30, 1879; application filed April 5, 1879.

To all whom it may concern Be it known that I, HENRY WARDEN, ofHannibal, Missouri, formerly of Philadelphia, Pennsylvania, haveinvented a new and useful Process for Oannin g Edibles, of which thefollowing specification is afull, clear, and true description.

My invention relates to the art of manufacturing, as an article ofcommerce, cooked or preserved perishable substances, such as edibles andthe like, packed into hermeticallysealed vessels.

Although my process is equally applicable to all perishable substancespreserved or cooked in air-tight vessels, yet, for greater simplicity inthis specification, I have described it applied to what is known ascompressed beef. Heretofore in the above manufacture it has been usualto first fill the can or vessel with meat, and then to solder a cap overthe opening in the can, leaving a vent-hole in the cap. The can orvessel is then submitted to heat, applied by hot water, steam, or otherconvenient means, to expel through the venthole the superfluous water,air, or other injurious substances. The vent is then sealed, and thevessel submitted to a further heat, sufficient to insure the properpreservation of its contents.

When it is desired to compress the contents ofthe vessel-as, forinstance, in putting up compressed beef--a flatsided tin vesselis used.

The venting expels part of the contents, as specified above, and whenthe can is cooled off the atmospheric pressure upon the outside of thecan carries the flat sides inward and compresses the remaining contents.This compression, however, is limited in its range, and can never exceedthe natural atmospheric pressure.

In my process, hereinafter described, I attain by artificial means anydesired pressure, and in addition, by the same means, cool the can,vessel, or package in a more speedy manner than heretofore, whilepreserving the seams or thin sides of the can from'injury by internalpressure. My process also enables the safe use of thethinnestmetal knownto commercein the formation of the cans, which are, in consequence,easily opened by the consumer. It also effects a saving of solder, andconsequently the cheaper making of the joints or seams of the cans.

Heretofore it has been attempted, after subjecting the can and contentsto the treatment first above described, and after closing the vent, toplace the can so sealedin aretort, and to introduce steam into theretort under high heat and pressure, to complete the cooking action. Thedifficulty, however, heretofore encountered in the use of the abovemethod has been to remove the can in safety from the retort withoutgreat loss of time, for, as will be readily understood, if the pressuresupon the outside and inside of the can are equal, and the door of theretort is opened for the removal of the cans, the pressure is taken fromthe outside of the cans, rendering the inside pressure liable to burstor explode them, to obviate which bursting it has been necessary to keepthe retort closed and allow a gradual cooling down, whereby, as stated,much time has been lost.

I am aware that retorts have been used for the purpose of cooking orpreserving and of pressing meats or vegetables contained in cans byadmitting thereto steam at proper pressures; but after the preservingand pressing are effected the cans are often found to be injuriouslyswollen or are burst by internal pressure when the retort is opened andthe outside pressure on them removed.

By my process all the above-described disadvantages are obviated andmany advantages, hereinafter described, are obtained.

My process consists substantially as follows: The first steps of thesame are those usual in the art of preserving hermetically sealed goods,and such as have been hereinbefore described. After the vent is closedthe can or vessel is placed in a retort or other closed vessel, intowhich steam or other fluids at proper temperatures and pressures areintroduced and maintained in order to effect the proper preservation ofthe contents. During the time the can or vessel is subjected to theabove heat and pressure the pressure from the interior of the can isnever greater than that upon the exterior thereof.

When the can or vessel is ready for removal from the retort or closedvessel, by reason of the contents having been sufficiently cooked orpreserved, I first reduce the temperature, but maintain the pressure inthe retort, and I' then obtain any pressure desired by pumping into theretort water or other cooling-fluids, to displace the steam or other hotfluids, at all times regulating the pressure given by the pump byattention to a gage affixed to the retort.

I also find that air can be substituted as a medium for keeping oraugmenting the pressure while lowering the temperature, and I do notwish to confine myself to any particular tluid to be used, for theessence of my invention lies in first replacing the hot pressure by acold pressure upon the outside of the can,

' which I effect by pumping in 'a cooling medium, and in then augmentingthe pressure of the cooling medium on the outside of the can or vesselat will, thus first replacing the hot pressure by a cold pressure, andthen augmentin g the cold pressure to any desired degree, so as tocompress the cans to any extent desirable, condensation meanwhile withinthe can or vessel relieving the internal pressure thereupon. I therebyproduce rapid cooling of the can or vessel and inclosed contents whilen11- der pressure and previous to their removal from the retort. I amalso enabled to cool cans or vessels with their contents more rapidlythan before, and also to secure the use of my retort in less time thanformerly for another lot of cans or vessels. I also by this processprotect any weak portions or parts of a can or vessel from any injuriousinternal strain or rupture.

I am likewise enabled to secure the above results when cooking orpreserving cans or vessels made with flat yielding sides or ends, orpackages made from any yielding or flexible material. I am also enabledto forcibly compress the contents of the can to any desired degreebeyond the degree of compression obtained by ordinary atmosphericpressure.

Having thus described my invention, I claim- 1. The improvement in theprocess of retorting canned edibles which consists in cooking filled andsealed cans in a retort under the pressure of a hot medium, in thencooling them under the pressure of a cooling medium while still in theretort, and in finally compressing them under an augmented pressure ofsaid coolin medium, substantiall y for the purposes set forth.

2. The introduction into a retort containing edibles in cans, and inwhich steam or other hot fluid exists under pressure, of a coolingmedium under any desired pressure greater than that of the hot fluid, soas to displace the steam or other hot fluid, for the purpose of loweringthe temperature within and augmenting the pressure upon the cans, forthe purposes set forth.

In testimony whereof I have hereun to signed my name this 25th day ofMarch, A. D. 1879.

HENRY WARDEN.

In presence of- J NO. E. THOMAS, J OSHUA P. RICHARDS.

